Screw expansion devices are well known in the orthodontic field to correct various dental abnormalities or occlusions. One of several types of orthodontic problems addressed by the present invention relates to an arch width or palate that is too narrow. This problem can also cause various other medical and dental difficulties. One general type of expansion device, commonly referred to as a rapid palatal expansion (RPE) device, includes a support apparatus having a screw mechanism. The support apparatus and screw mechanism are typically affixed to legs rigidly connected to teeth on opposite sides of the patient's maxillary jaw. As the screw mechanism is rotated, an expansive force may be applied to the palate. Successive expansions over time deliver the necessary forces for widening the palate. These devices are often used on narrow palates of children while the jaw and other dental structure are in formative stages For example, since the palate typically contains cartilage between the plates at earlier growth stages, palatal expanders are often a recommended course of treatment. It follows that the space available in the mouth of a child is relatively small and, therefore, size considerations and comfort issues become even more important in these cases.
Known orthopedic screw expansion devices are disclosed in U.S. Pat. Nos. 4,347,054; 5,002,485; and 5,281,133. As exemplified by these patents, expanders currently in commercial production include a screw unit for activation, four legs that are connected to molars and bicuspids of the patient and a supporting structure for maintaining structural integrity of the device. As also shown in these patents, the supporting structure of such typical devices may take up significant space within the mouth of a patient. Also, due to the size of the support structure, these devices cannot be situated at the uppermost arch region and cannot easily be used for mandibular expansion. U.S. Pat. No. 5,564,920 illustrates a palatal expander having a somewhat lower profile, however, the device is otherwise too complicated.
Another disadvantage of currently available orthodontic expanders is that the support structure can block the holes used for accepting a tool when actuating or turning the screw expander. Also, current expanders are typically substituted with a transpalatal arch after the expansion is complete to give the patient a more comfortable stabilizer at this stage of the treatment. Therefore, it has become apparent that improvements would be desirable in this general field to improve patient comfort and decrease any constraints on the use of such devices caused, for example, by the space consuming support structure. It would also be desirable to specifically reduce or even eliminate the need for substituting a palatal expander with a transpalatal arch.